Antifreeze composition



'hibitors in the antifreeze compositions.

United rates Patent 3,045,230 Patented July 24-, 1962 tine 3,046,230 ANTEFREEZE COMPOSITION Bernard H. Berger, Trenton, N.J., assignor to Cities Service Research and Development Company, New York, N.Y., a corporation of New Jersey No Drawing. Filed Aug. 19, 1959, Ser. No. 834,660 1 6 Claims. (Cl. 252-75) This invention relates to an improved antifreeze composition and more particularly to an improved antifreeze composition for use in cooling systems of internal combustion engines.

Antifreeze compositions comprising aqueous solutions of water soluble alcohols are commonly employed in the cooling systems of internal combustion engines to prevent freezing of the cooling medium during periods of cold weather. These compositions are used in systems in which they are in contact with different metals and with combinations of metals such as steel, iron, copper, etc. Corrosion of metals in the system is frequenly aggravated by electrolytic effects caused by contacting the antifreeze composition with the various metals used in the system. The presence of various metals in the system also complicates the problem of finding a suitable antifreeze composition since agents which are effective to inhibit corrosion of particular metals are frequently corrosive to other metals. Since antifreeze solutions must be formulated for use with systems containing different metals, it is, therefore, frequently necessary to employ various in- The problem is further complicated by the fact that the presence of one corrosion inhibitor may adversely affect the performance of other corrosion inhibitors in the same solution. It is therefore a matter of some importance to formulate antifreeze solutions containing the correct combinations of ingredients to insure proper protection against corrosion of the various metals commonly found in cooling systems.

Since most antifreeze solutions are distributed in concentrated form and diluted with water only when placed into actual use in the cooling system of an internal combustion engine, the effects of the antifreeze solution on metal storage containers must also be considered. Unfortunately, many antifreeze solutions which provide adequate protection against corrosion when diluted with water do not provide sufficient protection against corrosion of metal containers during storage in concentrated form.

This break-down of theantifreeze composition during storage is especially noticeable in the case of ethylene glycol antifreezes. It is, therefore, an object of this invention to provide an antifreeze composition which has improved resistance to corrosion of various metals during storage prior to use as well as when used in aqueous solutions in cooling systems.

In accordance with a preferred embodiment of the present invention, an antifreeze composition is provided the non-aqueous ingredients of which comprise a major proportion of a water soluble alcohol selected from the group consisting of low molecular weight monohydroxy aliphatic alcohols and low molecular weight dihydroxy aliphatic alcohols and which contains minor proportions of an alkali metal arsenite, an alkali metal mercaptobenzothiazole, an alkali metal metaborate, and an alkanol amine borate having the formula.

. where R, R and R are each selected from the group consisting of hydrogen and alkyl hydrocarbon radicals and at least one of R, R and R" is an alkyl hydrocarbon radical.

Alcohols suitable for use in antifreeze compositions of the present invention include monohydroxy and dihydroxy aliphatic alcohols of low molecular weight and are preferably present in amounts of between about and 99 weight percent of the total antifreeze composition. Suitable monohydroxy alcohols preferably contain one to six carbon atoms and include, for example, methanol, ethanol, propanol, etc., while suitable dihydroxy alcohols preferably contain two to six carbon atoms and include, for instance, ethylene glycol or propylene glycol. Mixtures of suitable monohydroxy alcohols or dihydroxy alcohols may also be used. Monohydroxy alcohols are commonly used in the preparation of volatile antifreeze compositions while dihydroxy alcohols are commonly used in the preparation of non-volatile or permanent type antifreeze compositions. While a variety of alcohols are suitable for use in antifreeze compositions of the present invention as described above, ethylene glycol is preferred for use in non-volatile type antifreeze compositions while methanol is preferred for use in volatile type antifreeze compositions.

The antifreeze compositions described herein are concentrated compositions containing only a minimum amount of water or other diluent and it is contemplated that such compositions will usually be diluted prior to use. While the antifreeze compositions of the present invention are intended primarily for use in the cooling systems of internal combustion engines, they may be utilized in a number of different fields in which dilute solutions are used under conditions Where temperatures may range below the freezing point of the diluent. When used in cooling systems the antifreeze compositions described herein are usually diluted with water to obtain a solution containing between about 10 and about 70 volume percent of the antifreeze composition but solutions containing other proportions of the antifreeze compositions are within the scope of the invention.

The alkali metal arsenite present in the antifreeze compositions of the invention is preferably present in amounts between about 0.25 and about 1.0 weight percent of the total antifreeze composition. Sodium arsenite is preferred but other alkali metal arsenites such as potassium arsenite are also suitable. Likewise, the preferred alkali metal mercaptobenzothiazole for use in antifrwze compositions of the present invention is sodium mercaptobenzothiazole while other alkali metal mercaptobenzothiazoles, such as potassium mercaptobenzothiazole, may be used. The alkali metal mercaptobenzothiazole salt used is preferably present in amounts between about 0.1 and about 0.6 weight percent of the total antifreeze composition and may conveniently be added to the composition as an aqueous solution of suitable strength such as for example a 50 weight percent solution.

ent as water of hydration, such as four moles or eight moles of water per mole of alkali metal metaborate. Sodium metaborate is a preferred alkali metal metaborate for use in the present invention but other alkali metal metaborates, such as potassium metaborate, are also suitable.

The alkanol amine borate is prefer-ably present in the antifreeze composition of the invention in amounts between about 0.2 and about 2.0 weight percent of the total antifreeze composition. Primary, secondary or tertiary &

alkanol amine borates are suitable for this purpose and where more than one alkyl group is present, these groups may be the same or mixed. While any alkyl groups which are readily soluble in the antifreeze composition may be present in the alkanol amine, the alkyl groups present in this compound preferably contain between one and six carbon atoms. A preferred alkanol amine borate for use in antifreeze compositions of the present invention is triisopropanolamine borate but other suitable alkanol amine borates such as triethanolamine borate, monoethyldiisopropanol amine borate, monopropyldiisobutanol amine borate, diisopropanol amine borate, methanol amine borate, monohexyldipentanol amine borate, etc. may be used.

It has been found, quite unexpectedly, that not only do antifreeze compositions of the types described above provide good protection against corrosion but also that such compositions which contain alkali metal arsenite, alkali metal mercaptobenzothiazole, alkali metal metaborate and alkanol amine borate are far more resistant to corrosion than compositions which contain some but not all of these ingredients. This unexpected superiority of the above described anti-freeze compositions in resisting corrosion of various metals is clearly demonstrated by the data presented below.

The ingredients incorporated in antifreeze compositions of the present invention may be mixed in any suitable manner. For instance, normally solid ingredients may be dissolved directly in all or a portion of the liquid components of the composition. Normally solid ingredients may be dissolved in small amounts of suitable solvents such as water or alcohol and the resulting solutions used in formulating the antifreeze composition.

Since the usual commercial practice is to distribute antifreeze compositions in concentrated form for dilution with water immediately prior to use, it is usually desirable to use as little water or other diluent as possible in formulating antifreeze compositions since additional diluent merely increases the quantity of solution which must be transported and stored prior to use. It is frequently desirable, however, to use small amounts of water to aid in mixing the various ingredients of the above described antifreeze compositions. Also, small amounts of water are frequently present in commercial alcohols such as ethylene glycol. Water is, therefore, frequently present in antifreeze compositions of the present invention in quantities of between about 1.0 and about 5.0 weight percent of the antifreeze composition and larger amounts of water may of course be present after such composition has been diluted for use or if such composition is deliberately prepared with additional water.

In addition to the ingredients described above antifreeze compositions of the present invention may include small amounts of other ingredients such as anti-foam agents, dyes for importing desired color properties or other special purpose additives. Suitable antifoam agents may include, for example, commercial silicon emulsions as well as polyglycol antifoam agents. A suitable polyglycol antifoam agent is, for instance, a polypropylene glycol having a molecular weight of about twelve hundred. Both silicon and polyglycol antifoarn agents may be used separately or together in suitable amounts. For instance, where a silicon antifoam agent is used it is frequently present in amounts between about 0.001 and about 0.01 weight percent of the antifreeze composition while polyglycol antifoam agents when used are frequently present in amounts between about 0.05 and about 0.2 weight percent of the total antifreeze composition. If special color properties are desired in the finished antifreeze composition, suitable color dyes may be used and such dyes are frequently present in amounts between about 0.0005 and about 0.005 weight percent of the antifreeze composition.

Many various antifreeze compositions may, of course, be formulated in accordance with the present invention and the compositions described below are merely indicative of the various types of antifreeze compositions contemplated by the invention. The following compositions illustrate by way of example antifreeze compositions which may be formulated in accordance with the invention. In each case the amount of each ingredient is expressed as a weight percent of the total composition.

EXAMPLE 1 A suitable antifreeze composition of the present invention which is effective in resisting corrosion of various metals may, for example, contain the following ingredients expressed as weight percent of the total antifreeze composition exclusive of any additional water or other diluent which may be added at the time of formulation or subsequently.

Another suitable antifreeze composition may contain the following ingredients.

Ingredients: Weight percent Ethylene glycol 96.5 Sodium arsenite 0.3 Sodium mercaptobenzothiazole 0.2 Sodium metaborate 1.5 Triisopropanolamine borate 2.0

EXAMPLE 3 Another suitable antifreeze composition in accordance with the present invention includes the following ingredients.

Ingredients: Weight percent Methanol 97.45 Sodium arsenite 0.25 Sodium mercaptobenzothiazole 0.1 Sodium metaborate 2.0 Triisopropanolamine borate 0.2

EXAMPLE 4 Another suitable antifreeze composition in accordance with the invention comprises the following ingredients.

Ingredients: Weight percent Ethylene glycol 90.2 Water 5.20 Potassium arsenite 1.0 Potassium mercaptobenzothiazole 0.5 Potassium meta-borate 1.8 Hexanolamine borate 1.5

EXAMPLE 5 Still another suitable antifreeze composition in accordance with the invention contains the following ingredients.

Ingredients: Weight percent Ethylene glycol 97.15 Water 1.0 Sodium arsenite 0.25 Sodium mercaptobenzothiazole 0.1 Potassium metaborate 0.5

Triethanolamine borate 1.0

EXAMPLE 6 Yet another suitable antifreeze composition of the present invention contains the following ingredients.

Ingredients: Weight percent Propylene glycol 86-9 Sodium arsenite 0.5 Sodium mercaptobenzothiazole 0.3 Sodium metaborate 1.6 Polyglycol anti-foam agent. 0.2 Diisopropanolamine borate 0.5

EXAMPLE 7 Another suitable antifreeze composition in accordance with the invention contains the following ingredients.

as indicated below. This antifreeze composition was prepared by filling a mixing tank with the desired amount of ethylene glycol to which sufiicient water was added to bring about the desired amount of water in the finished antifreeze composition. After the ethylene glycol and water were mixed thoroughly, a sufficient amount of a 42.5 percent aqueous solution of sodium arsenite was added by mixing thoroughly to yield the desired amount of sodium arsenite in the finished composition. Following this a sufiicient amount ofa 50% aqueous solution of sodium mercaptobenzothiazole was added to yield the desired amount of sodium mercaptobenzothiazole in the finished compostion. Similarly, a sufiicient amount of eight mole sodium metaborate was mixed thoroughly with the previous ingredients to provide the desired amount of sodium metaborate in the finished composition and a suflicient amount of triisopropanolamine borate was mixed thoroughly with the previous ingredients to provide the desired amount of triisopropanolamine borate in the finished antifreeze composition. Following Ingredients; W i h percent these mixing operations, appropriate amounts of polygly- Ethylene glycol 80.94 0 1 and silicon antifoarn agents were added. Finally a Propylene glycol 14 suflicient amount of green dye was added to yield the Water w 2,5 desired color. Potassium arsenite 0.4 2 n r r o fully evaluate the antifreeze composition Sodium mercaptobenzothiazole 0.3 Of ample 1, Which is designated as composition A Sodium 'metabora-te 0,8 below, additional antifreeze COInpOSitions designated B Polyglycol anti-foam agent 0.05 hro gh H, J, K and L were prepared containing the fol- Silicon anti-foam agent 0.01 lowi g ingredients expressed as weight percent of the Monoethyldiisopropanolamine 'borate 1.0 total composition as shown in Table I.

Table I ANTIFREEZE COMPOSITIONS Weight Percent Ingredients A B o D E F o H .T K L Ethylene GlyooL- 95.869 92.844 97.207 96.657 96.207 96.867 96.159 97.659 95. 354 95.194 97.344 r 2.5 3.35 1.86 2.09 2.38 2.03 1.57 1.57 3.2 3.17 2,05 Sodium Arsenite 0.34 0.33 0.33 0-33 0.33 0.33 0.3 Sodium Mercaptobenzothiazole 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.17 Sodium Metahorate 0.48 1.2 0-48 0.48 1.2 1.2 Triisopropanolamlne Borate 0. 5 0. 0. 50 0- 50 0.50 2- 00 0.50 PolyglycolAntifoam Agent 0.10 0.10 0.10 0.10 0.10 0.10 o. 10 0.10 0.10 0.10 Silicone Antifoam A ent 0.005 0.005 0.005 0.005 Green Dye 0.001 0. 001 0.003 0.003 0.003 0.003 0.001 0.001 0. 001 0.001 0.001

EXAMPLE 8 The corrosive effects of antifreeze compositions A Another antifreeze composition in accordance with the invention contains the following ingredients.

Ingredients: Weight percent Ethanol 97.8 Sodium arsenite 0.5 Sodium mercaptobenzothiazole 0.2 Sodium metaborate 0.5 Methanolamine borate 1.0

EXAMPLE 9 Still another antifreeze composition in accordance with the invention contains the following ingredients.

EXAMPLE 10 In order to test the effectiveness of antifreeze compositions of the present invention in resisting corrosion of various types of metals the antifreeze composition described in Example 1 above was formulated and tested through H, J, K and L described above were tested with respect of steel, copper, brass, solder, cast aluminum and cast iron by the use of the ASTM glassware corrosion test D-l384 as modified by General Motors specification 1899-M. In this test one inch by two inch specimens of the various metals .used are uniformly cleaned, polished, weighed and bolted together on an insulated rod with one-quarter inch spacers between the specimens. The spacers are made from one of the two adjoining metal specimens except that a non-conducting material is used between brass and steel. The cast iron, cast aluminum and solder specimens are one-eighth inch thick while the steel, copper and brass specimens are one-sixteenth inch thick. The steel specimen is SAE 1020 cold rolled steel. The specimen bundle is placed in a one liter tall form beaker with 250 milliliters of the antifreeze composition being tested and 750 milliliters of synthetic hard water standardized to contain 300 p.p.m. of sulphate ion and p.p.m. chloride ion (sodium salt in both cases). The beaker is fitted with a gas dispersion tube which extends to the bottom of the beaker. The solution is maintained at F. and the aeration rate is set at 100 milliliters per minute. After 336 hours the specimens are removed from the solution, examined visually, cleaned free of corrosion products, dried and weighed. Corrosion losses are reported as milligrams per specimen. The results of this glassware corrosion test of the antifreeze compositions A through H, J, K and L are shown in Table II.

Table II GLASSWARE CORROSION TEST RESULTS Antifreeze Composition Weight Loss per Specimen (mg) A B C D E F G H J K L Copper 4. 4 4. 7 12. 6 8.0 46.6 5. 7 8.1 6. 5 6. 4 9. 7 4. 5 Brass- 5.0 6. 3 11. 3 6. 4 9. 3 6. 6 5. 5 8. 5 8. 4 6. 6 5.0 Solder 5. 6 7. 6 177. 5 16.1 12. 5 8. 6 11.4 17. 4 38.0 7.0 6. 4 Cast Aluminum Preclean 11.4 16.1 1. 9 1. 9 6.5 4. 7 3. 7 0.7 15. 7 42. 5 11.3 Cast Aluminum Postclean 16. 8 48. 7 112. 5 23. 4 211.1 78. 7 22. 5 7. 5 73.2 77. 2 82. 3 Steel 1. 7 1. 5 1.9 87. 5 3.7 1.3 5.8 223.4 49.4 1.3 43.8 Cast Iron 1. 6 0. 2 80. 3 12.1 3.1 7. 5 9. 3 153.0 25.5 0.9 4. 2

Total Weight loss 011g.) 46. 5 85. 1 398. 155. 4 292. 8 113. l 66. 3 417. 0 216.6 145.2 157. 5

' Wiped clean with acetone.

The results shown in Table II indicate very clearly not only that the antifreeze composition of Example 1 (composition A) provides good corrosion resistance for various metals but also that the antifreeze composition of Example 1, which contains sodium arsenite, sodium mercaptobenzothiazole, sodium metaborate and triisopropanolamine borate, is far superior in resisting corrosion to the antifreeze compositions B through H, J, K and L which differed from composition A only in that they did not contain all four of these corrosion inhibitors. The presence or absence of the polyglycol or silicon antifoam agents obviously had no effect on the corrosion characteristics of antifreeze compositions. The superiority of composition A as compared with compositions B through H, J, K and L is completely unexpected and makes possible the formulation of antifreeze compositions which are surprisingly superior to those which do not contain all four of the corrosion inhibitors present in composition A. It is not known why these unexpected results are obtained but this surprising effect is probably due to the inter-action of the various corrosion inhibiors according to presently unknown mechanisms or to variations in effect upon the various metals of combinations of these inhibitors for similarly unknown reasons.

In connection with Table II it should be especially noted that not only did composition A result in substantially less total corrosion of the metal specimens than any of he other compositions tested but also that each of the other compositions tested presented a serious problem with respect to one or more of the metal specimens. Composition A containing all four of the above mentioned corrosion inhibitors was the only composition tested which provided satisfactory corrosion protection for all of the metal specimens.

To further test the effectiveness of the antifreeze composition A described above in comparison with other antifreeze compositions, several commercial antifreezes obtained on the open market and designated below as antifreeze compositions M, N, O and P were also subjected to the same glassware corrosion test described above. The results of these tests are shown in Table III below.

Table III GLASSWARE CORROSION TEST RESULTS FOR COMIIVIER- CIAL ANIIFREEZES Antifreeze Composition Weight Loss per Specimen e) A M N O P Copper 4 4 13.3 7. 5 12.2 Brass 5 0 16.4 8.2 25. 5 54.1 Solder 5. 6 21. 5 13. 3 57. 2 9. 5 Cast Aluminum Preclean 11.4 6. 2 15.4 7. 7 10. 5 Cast Aluminum Postclean 16.8 45. 7 88. 5 41. 4 39. 5 Steel 1 7 10.0 2.5 497.2 165.4 Cast Iron 1 6 116.0 0.4 258. 5 106.8

Total weight loss For footnotes a and b see Table II.

Table III demonstrates quite clearly that composition A is far superior to any of the four commercial antifreezes tested. It might be noted that composition A not only resulted in far less total corrosion of the metal specimens than did any of the commercial antifreezes tested but also that the various commercial antifreezes produced totally unacceptable amounts of corrosion with respect to one or more of the metal specimens. It is thus apparent that composition A, formulated in accordance with the present invention, is superior in all respects to any of the four commercial antifreezes tested.

While the invention has been described with respect to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended to cover all such changes and modifications in the appended claims.

I claim:

1. An antifreeze composition the aqueous portion of which consists essentially of water and the non-aqueous portion of which consists essentially of a water soluble alcohol selected from the group consisting of low molecular weight monohydroxy aliphatic alcohols having from to to 6 carbon atoms and low molecular weight dihydroxy aliphatic alcohols having from 2 to 6 carbon atoms and which contains between about 0.25 and about 1.0 weight percent alkali metal arsenite, between about 0.1 and about 0.6 weight percent alkali metal mercaptobenzothiazole, between about 0.5 and about 2.0 weight percent alkali metal metaborate and between about 0.2 and about 2.0 weight percent of a compound having the wherein R, R and R" are each selected from the group consisting of hydrogen and alkyl hydrocarbon radicals having from 1 to 6 carbon atoms and at least one of R, R and R" is an alkyl hydrocarbon radical.

2. A non-volatile type antifreeze composition the aqueous portion of which consists essentially of water and the non-aqueous portion of which consists essentially of ethylene glycol and which contains between about 0.25 and about 1.0 weight percent alkali metal arsenite, between about 0.1 and about 0.6 weight percent alkali metal mercaptobenzothiazole, between about 0.5 and about 2.0 weight percent alkali metal metaborate and between about 0.2 and about 2.0 weight percent of a compound having the formula wherein R, R and R" are each selected from the group consisting of hydrogen and alkyl hydrocarbon radicals having from 1 to 6 carbon atoms and at least one of R,

R and R is an alkyl hydrocarbon radical.

3. A permanent type antifreeze composition the aqueous portion of which consists essentially of water and the non-aqueous portion of which consists essentially of ethylene glycol and which contains between about 0.25 and about 1.0 weight percent sodium arsenite, between about 0.1 and about 0.6 weight percent sodium mercaptobenzothiazole and between about 0.5, about 2.0 weight percent sodium metaborate and between about 0.2 and about 2.0 weight percent triisopropanolamine borate.

4. An antifreeze composition the aqueous portion of which consists essentially of water and the non-aqueous portion of which consists essentially of methanol and which contains between about 0.25 and about 1.0 weight percent alkali metal arsenite, between about 0.1 and about 0.6 weight percent alkali metal mercaptobenzothiazole, between about 0.5 and about 2.0 weight percent alkali metal metaborate and between about 0.2 and about 2.0 weight percent of a compound having the wherein R, R and R are each selected from the group consisting of hydrogen and alkyl hydrocarbon radicals 10 having from 1 to 6 carbon atoms and at least one of R, R and R is an alkyl hydrocarbon radical.

5. A non-volatile type antifreeze solution consisting essentially of ethylene glycol and containing between about 1.0 and about 5.0 weight percent water, between about 0.25 and about 1.0 weight percent sodium arsenite, between about 0.1 and about 0.6 weight percent sodium mercaptobenzothiazole, between about 0.5 and about 2.0 weight percent sodium metaborate and between about 0.2 and about 2.0 weight percent triisopropanolamine borate.

6. A non-volatile type antifreeze solution consisting essentially of ethylene glycol and containing about 2.5 weight percent water, about 0.34 weight percent sodium arsenite, about 0.17 weight percent sodium mercaptobenzothiazole, about 0.48 weight percent sodium metaborate, about 0.5 weight percent triisopropanolamine borate, about 0.10 weight percent polyglycol antifoam agent (molecular weight about 1,200), and about 0.001 weight percent of a dye to impart a desired color.

References Cited in the file of this patent UNITED STATES PATENTS 1,992,689 Cox Feb. 26, 1935 2,126,173 Clapsadle et al. Aug. 9, 1938 2,312,208 Clayton et al. Feb. 23, 1943 2,534,030 Keller Dec. 12, 1950 2,566,926 Burghart Sept. 4, 1951 2,803,604 Meighen Aug. 20, 1957 2,960,473 Meighen et al Nov. 15, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,046,230 July 24, 1962 Bernard H. Berger It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 13, for "compostion" read composition column 7, line 38, for "inhibiors" read inhibitors line 44, for "he" read the column 8, line 42, for "to" first. occurrence, read I Signed and sealed this 1st day of January 1963.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attcsting Officer Commissioner of Patents 

1. AN ANTIFREEZE COMPOSITION THE AQUEOUS PORTION OF WHICH CONSISTS ESSENTIALLY OF WATER AND THE NON-AQUEOUS PORTION OF WHICH CONSISTS ESSENTIALLY OF A WATER SOLUBLE ALCOHOL SELECTED FROM THE GROUP CONSISTING OF LOW MOLECULAR WEIGHT MONOHYDROXY ALIPHATIC ALCOHOLS HAVING FROM TO TO 6 CARBON ATOMS AND LOW MOLECULAR WEIGHT DIHYDROXY ALIPHATIC ALCOHOLS HAVING FROM 2 TO 6 CARBON ATOMS AND WHICH CONTAINS BETWEEN ABOUT 0.25 AND ABOUT 1.0 WEIGHT PERCENT ALKALI METAL ARSENITE, BETWEEN ABOUT 0.1 AND ABOUT 0.6 WEIGHT PERCENT ALKALI METAL MERCAPTOBENZOTHIAZOLE, BETWWEN ABOUT 0.5 AND ABOUT 2.0 WEIGHT PERCENT ALKALI METAL METABORATE AND BETWEEN ABOUT 0.2 AND ABOUT 2.0 WEIGHT PERCENT OF A COMPOUND HAVING THE FORMULA 